Telephone system



' 1931} s. c. WlNFlELD-SMITH 1,833,586

TELEPHONE SYSTEM Filed Nov. 2, 1929 2 Sheets-Sheet 1 Dec. 29,. 1931. s. c. WlNFlELD-SMITH 1,338,536

TELEPHONE SYSTEM Filed Nov. 2, 1929 2 Sheets-Sheet 2 u via/Tan Patented Dec. 29, 1931 UNITED er-arse ElTEPHENCHRISTOPI-IER XHINFIELB-SMITH, 01" LONDON, ENGLAND, ASSIGNOR T0 BUROVOX, LIMITED, OF LQNDQN, ENGLAND TELEPHONE SYSTEM Application filed. November z, 19539, Serial No. 4%,356, and in Great Britain November 15, 1928.

This invention relates to telephone systems of-the house, inter-oiiice or like variety,

asdistinct from public or post-office tele phone systems.

he invention is directed to the provision of a system which enables a principal to comrnunicate with a subordinate or other party by pressing a button or-otherwise operating a switch, receive the answering call upon a loud speaker and is enabled to answer the party he has called by speaking from a distance into a sensitive microphone.

An object of the present invention in a system of the above character, is to aiiord the principal knowledge of the moment when the called partyis listening-in so that he may be warned that conversation at his end is audible to the party he has called.

A furtherlobject is to provide means whereby acontrol may be exercised by the principal so that when he receives the signal that the,

party he has called is prepared to listenin, he may be prevented from doing so until the principal desires.

According to the invention the system coinprises a switch at the principals end for calling', by buzzer or otherwise, the party to whom he desires to speak, a signaldevice at the principals end, such as a lamp or other visible indicator, or a buzzer or other audible indicator, which is actuated by the operation of a switch at the called station so soon as the party in question is prepared to listen as by the raising of his receiver from a stand or by manipulating a finger switch upon the receiver, or otherwise completing a listening circuit.

According to the preferred arrangement, when the called party operates the switch preparatory to listening, he makes the principals microphone circuit and his own micro phone circuit including the loud speaker at the principals station together with a circuit which actuates'the signal atthe principals statlon. Where 1t 18 desired as an additlonal safeguard to provide the principal with =av control such that the called party,

receiver to --t he eilect that the called party 5 is ready listen, he establishes the partys listening circuit by operating the control switch so that it will be seen that although the called party is ready to listen he cannot listen until the calling party so desires.

According to the invention, the circuit may be established between two stations, or between one station and any of a plurality of stations. The invention may be applied, for exan iple, in conne tion with nianagers oflice, to theinstruinents of various subordinat-es, or it can be applied to ships cabins and connected with the ships steward or other service or services or, in any other situation where it is desired that a principal should be put to as little trouble as possible incommunicatinp; with the party he desires to call,

while maintainin secrecy as to that which is adapted to connect this common line with L the two independent speaking lines to complete the said circuits. The signal or indicating device the principals station is operated either directly or indirectly by the current which flows in one or other of the micro-- phone circuits as soon as the line containing the battery is connected up.

In a modified arrangement the signal or indicating device is operated by current which flows in a parallel circuit to that flow ing' in the principals microphone as soon as the circuit thereof is completed by the closing of the switch at the distant station.

Referring now to the accompanying drawings which show embodiments of the invention 7 Figure 1 shows a simple form of telephone system adapted for use in ships cabins and :the like. l

Figure 2 shows a slightly modified circuit to that shown in Figure 1.

Figure 8 shows a multi-station circuit for use in residences, offices and ships cabins and the like.

In the drawings, at A, A, A and A is indicated telephone stations which may be in rooms, oflices or ships cabins from which calls may be originated and controlled, station B being the called station and may be the servvants or stewards quarters, a staff office or the like.

In Figure 1, the apparatus at station A comprises a loud-speaking telephone a, a sensitive microphone b, a ring key 0 and a signalling device (Z shown as a lamp. These devices are wired to station B over lines 1, 2, 3 and A, line 1 being connected to the receiver a at station A to microphone e at station B, wire 2 connecting microphone b at station A and receiver f at station B, these circuits being independent except for the common battery feed. V-Jire 3 is the common battery feed wire and line 4 the signalling or ringing wire. The apparatus at station B further comprises the battery 9, alarm device 71 and a hand microphone operated switch A call from station A is originated by operating key 0 causing operation at station B of the alarm device It shown as a buzzer. The attendant at station B lifts the microphone and receiver combination of the supporting arm i of switch 7' and thereby connects battery to his receiver 7 and microphone e in parallel, the arm z' opening the ringing circuit at its normally closed contact. Key 0 remains closed, thus establishing speaking circuits through the microphones and receivers at stations A and B, the signalling lamp (Z at station A glowing to indicate to the caller that the called party is listening. The calling party can prevent the called party from overhearing by opening key 0 which opens the speaking circuit from station A to station B, the lamp (Z being extinguished to indicate to the caller that overhearing is not taking place. The called party replies by speaking into his microphone e and is heard by means of receiver a at station A.

If a call is to be originated from station B, this is effected by the caller lifting his microphone and receiver combination and calling to the party at station A by means of his receiver a. the called party establishes the speaking circuit from station A to station B by operating key 0.

The circuit shown in Figure 2 is similar to that shown in Figure 1. The apparatus of station A includes a relay an adapted to operate when battery is connected to receiver a, this relay closes a circuit for signalling lamp (Z which is shown as being fed by a local battery but the lamp may be fed from the main battery 9. The ringing key 0 in 1,eas,5 c

this modification serves purely as a ringing key and communication is established by operation of switch j at station B, microphone c and receiver f being connected to independent leaf springs upon switch j.

In Figure 3 a system comprising a plurality of stations of which three are indicated by A, A and A is shown, the stations being connected to a central station B.

The apparatus at stations A, A and others comprises receivers a, microphones 5, signalling devices (l and in addition ringing keys 0 and overhearing control switches 19.

Apparatus at station B comprises microphone c, receiver f, microphone and/or receiver support 2" adapted when the device is lifted off to close the speaking circuits at that station. A central battery 9 and buzzer or other signalling device It is also provided. In addition the apparatus includes a dual switch having two sets of contacts 9 and 1" with associated contact arms .9 and 25 respectively connected to the microphone e and the receiver The incoming line wires 1 and 2 terminate upon contacts g and r, and arms 3 and z? are synchronously operable so that the operator at station B may establish communication with any of the parties at stations A, A and others. A multiple indicator u of known type is provided at station B and is Wired in series with buzzer h to the ringing keys 0 at station A, A and others. Closure of any key 0 effects operation of the corresponding indicator device and operation of buzzer it, the operator noting which indicator is operated rotates the selecting switch arms 8 and z to the appropriate contacts in the contact sets g and r and establishes communication with the caller. The indicator is re stored to normal by momentary depression of key '0.

The operation for setting up a call is substantially similar to that described in connection with Figure 1, the caller at stations A, A and others originating calls by operat ing keys 0. The operator at station B, noting upon the indicator u where the call originates from, rotates his switch arms 8 and t to the terminals of the callers line wires before closing switch arm 2' to prevent clicks in other receivers. The operator may speak to the calling party by means of microphone e at station B and receivers a, at the calling partys station, the calling party replying by means of his microphone and receiver f at station B Overhearing may be prevented by operating switch 79 which opens the microphone circuit as in Figure 1, signal lamp 1) indicating to the caller that the operator may be listening when this switch is closed.

I claim:

1. In a telephone system of the kind referred to, a principals and a subordinates station, a transmitter at said principals station, a line wire from said transmitter to a receiver at thesubordinates station, a receiver at said principals stations and a line wire from said receiver to a transmitter at the subordinates station, an electric current source at the subordinates station and a line wire therefrom to the principals station, a calling device at the subordinates station and a line Wire therefrom to the principals station, an instrument operated switch at the subordinates station normally connecting said battery and calling device but adapted when operated to connect said battery to a connection between the receiver and transmitter at said subordinates station, a manually operated switch at the principals station for closing said calling device circuit, and an indicating device at the principals station for indicating to the principal that the subordinate is capable of overhearing.

2. In a telephone system of the kind referred to, a principals and a subordinates station, a transmitter at said principals station, a line wire from said transmitter to a receiver at the subordinates station, a receiver at said principals stations and a line wire from said receiver to a transmitter at the subordinates station, an electric current source at the snborninates station and a line wire therefrom to the principals station, a calling device at the snbordinates station and a line wire therefrom to the principals station, a manually operated switch at the principals station for establishing connection to th; subordinates station and an indicating device operated by microphone current at the principals station for indicating that the snoordinate is capable of overhearing.

3. In a telephone system of the kind referred to, a principals and a subordinates station, a transmitter at said principals station, a line wire from said transmitter to a receiver at the subordinates station, a receiver at saic principals stations and a line wire from said receiver to a transmitter at the subordinates station, an electric current source at the subordinates station and a line wire therefrom to the principals station, a calling device at the subordinates station and a line wire therefrom to the principals station, a manually operated switch at the principals station for establishing connection to the subordinates station and an indicating device operated by receiver current at the principals station for indicating that the subordinate is capable of overhearing.

4. In a telephone systemot the kind referred to, a principals and a subordinates station, a transmitter at said principals station, a line wire from said transmitter to a receiver at the subordinates station, a receiver at said principals stations and a line wire from said receiver to a transmitter at the subordinates station, an electric current source at the subordinates station and a line wire therefrom to the principals station, a

calling device at the subordinates station and a line wire therefrom to the principals station, a manually operated switch at the principals station for calling a subordinates station said switch being capable of opening the microphone circuit at the principals station so as to prevent overhearing at the subordinates station.

5. Ina telephone system a plurality of stations and a central station, transmitters at each station capable of connection to a receiving device at the central station, receiving devices at said stations capable of connection to a transmitting device at the central station, an electric current source at the central station and a common connecting line wire therefrom to the other stations, an indicating device at the central station capable of selective operation from any station and a calling device at the central station operable from said other stations.

6. In a telephone system a plurality of stations and a central station, receiving and transmitting devices at said stations,switching arrangements at said stations for establishing speaking connection bet een any one of said stations and the central station and a signal device at each of said stations operated by transmitter current and adapted to indicate to the operator that said transmitter is energized and that overhearing may take place.

7. In a telephone system of the kind referred to, a plurality of stations and a central station, a dual-armed switch at said central station, a transmitter connected to one of said dual arms and a transmitter connected to the other arm, a connection between said transmitter and receiver to a current source over an instrumentactuated switch, line wires from the contacts associated with the switch arm connected to the receiver to transmitters at the other stations, line wires from the contacts associated with the switch arm connected to the transmitter to receivers at the other stations, a signal device at the central station, a selective indicator device at the central station, a switch at each of the other stations for signalling to the central station, a transmitter current operated signal device at the other stations for indicating that an operator at the central station is capable of overhearing and a switch at the other stations for opening the circuit of the transmitter at said other stations until the operator thereat is prepared to speak to the operator at the central station.

In testimony whereof I have signed my name to this specification.

STEPHEN CHRISTOPHER WlNFlELD-SMITHJ 

